The best place to retire in mexico?

If i wont to bay a house or condo or something similar,where I can get the best price in Mexico

I think it depends on what you're looking for. Cheap cost of living or beachfront property with lots of Americans nearby?
At some point you will need to make a trade-off between convenience and cost. I live in Pachuca, only 55 miles from Mexico City but very cheap, clean air and most services as it is the capital of Hidalgo state. On the down side it's rather cold here at times during December and January. And don't listen to the nonsense that says you'll never really own your property. Yes there are rules and guidelines but unlikely that the government would take your property away from you In fact if you live and work long enough in Mexico as I have, the government helps you buy a house and your employer provides most of the capital.

Tjuana!

near some clear water

Buying property in Mexico makes as much sense as buying a condo on an Indian Reservation. You think you "own" it but you never will, no matter what kind of paper they give you or what their Supreme Court says. If relations with the US go south they will nationalize all property owned by US citizens in a heartbeat.
If you want to buy property in Mexico then keep a packed bag by the door and plenty of gas in the car.
The only thing Mexico wants to give to the US is more of it's poorest citizens. Certainly not any of it's land.

The Baja Riviera from Rosarito to Ensenada is blooming with condos and planned communities, some available from the low 100,000s. Close to the US Border. Many sites on the Internet for Remax and Coldwell Banker.Better hurry, they're going fast.New laws protect foreign buyers and they are encouraged by the government.

Acapulco, Guerrero.....